Communicating about quantity without a language model: number devices in homesign grammar.

Area of Science:

• Linguistics
• Developmental Psychology
• Cognitive Science

Background:

• Natural languages possess formal devices for number, including lexical and grammatical elements.
• The origin of linguistic number systems in the absence of conventional language input remains an open question.
• Homesigns, spontaneously developed gestural systems by deaf individuals lacking language exposure, provide a unique context to study language emergence.

Purpose of the Study:

• To investigate whether linguistic devices for number arise in communication systems not transmitted generationally.
• To examine the development and characteristics of number gestures in homesigners.
• To determine the source of linguistic number patterns in homesign systems.

Main Methods:

• Study 1: Analyzed number gestures produced by four adult homesigners and their hearing communication partners.
• Study 2: Examined number gestures of a child homesigner and his hearing mother to trace developmental origins.
• Qualitative analysis of gesture form and function within the homesign systems.

Main Results:

• Adult homesigners produced both cardinal (enumeration) and non-cardinal (one vs. more than one) number gestures.
• Homesigners' number gestures were linguistic, integrated into their systems and resembling established sign language number signs.
• Child homesigners displayed all adult patterns, while hearing partners showed only some, suggesting homesigners, not partners, originate these linguistic features.

Conclusions:

• Linguistic number devices can emerge early in homesign development without conventional language input.
• Hearing communication partners are unlikely to be the source of homesigners' linguistic expressions of non-cardinal number.
• The findings indicate that linguistic number is fundamental to language and can arise spontaneously in novel communication systems.